H.I.D. (High Intensity Discharge) Plant Grow Lights
H.I.D. lights are the undoubtedly the best grow lights available today. There are two types of H.I.D. (High Intensity Discharge) lamps that have suitable spectrums and intensity for plant growth.
1.]MH (Metal Halide) Emit a blue light spectrum, similar to the Summer sun.
2.] HPS (High Pressure Sodium)Emit a red/yellow spectrum similar to the Autumn sun.
Metal Halide - MH bulbs are highly efficient, they produce between 70 and 115 lumens of light output per watt of electricity used. MH (Metal Halide) Their blue spectrum emission promotes rapid plant growth. They also promote compact plants with shorter internodal foliage spacing.
The average lifespan of an MH bulb is approximately 10,000 cumulative hours. The bulb will light up beyond this point but due to the gradual decline of light, will become increasingly ineffective. If you compare their lumen (brightness) per unit of energy consumed, metal halides produce up to 125 lumens per watt compared to 39 lumens per watt with standard fluorescent lights and 18 lumens per watt for standard incandescent bulbs.
MH (Medal Halide) bulbs should be replaced about every 10,000 hours of use or approximately 18 months (as per an 18 hour / day on cycle).
The bulbs themselves need to be burned in a specific position. They come in three types: Vertical (marked BU or BD), Horizontal (marked HOR) and Universal (marked U). The universal bulbs can be burned in any position, but they still are more efficient when burned vertically.
High pressure sodium bulbs emit an orange-red glow. This band of light triggers hormones in plants to increase flowering/budding in plants. They are the best grow lights available for secondary or supplemental lighting (used in conjunction with natural sunlight). This is ideal for greenhouse growing applications.
Not only is this a great flowering light, it has two features that make it a more economical choice. Their average lifespan is twice that of metal halides, however - after 18,000 hours of use, they will start to draw more electricity than their rated watts while gradually producing less light. HPS bulbs are very efficient. They produce up to 140 lumens per watt. Their disadvantage is they are deficient in the blue spectrum.
If a gardener were to start a young plant under a HPS bulb, she/he would see impressive vertical growth. In fact, probably too impressive. Most plants would grow up thin and lanky and in no time you will have to prune your plant back before it grows into the light fixture. The exception to these drawbacks is using HPS grow lights in a greenhouse or in conjunction another light source that emits light in the blue spectrum. Light sources that have a high output in the blue spectrum like sunlight and MH grow lights offset any stretching caused by HPS bulbs.
For plants that normally bud and flower in the fall an HPS (High Pressure Sodium) is usually the light of choice because it's light spectrum promotes flower production.
There are also color corrected HPS (High Pressure Sodium) bulbs available for improved growing efficiency. These are designed specifically for indoor horticulture, and have a more balanced color spectrum.
HPS bulbs should be changed no later than 24 months from initial use. These bulbs (like the Metal Halides) also slowly decrease in brightness and hence efficiency over time, in order to maintain the proper light intensity these bulbs should be changed at the end of their rated life.
Conversion lamps are HPS lamps that are operated with standard metal halide ballasts.
Enhanced Spectrum Lamps are top rated horticultural lamps due to their increased output in the Blue spectrum, giving the best combination of light for both growth, and flowering. They are also a variety of HPS
Due to the heat that is emitted from these types of fixtures, you should hang them according to size. Smaller wattage systems (100 and 250) should be hung about 2 to 3 feet from the top of the plants. Medium wattage systems (400 and 600) should be hung around 4 feet from the top of the plants. High wattage systems (1000 and up) should be placed at least 4 to 6 feet from the plant tops.
Day / Night Cycle.
Plants need the darkness as well as sunlight, so do not leave your Hydroponic / Horticultural lights running 24/7 .The lights run time depends on the variety of plant. Most ornamental plants and vegetables need about 10 to 12 hours of light to promote healthy growth. Plants that produce fruits or flowers will show improvement with up to 16 hours a day of supplemental light.
Operating Cost for Hydroponic Lighting Systems
To calculate the cost of operating a Lighting System ,take the lights combined wattage, and divide it by 1000 to get the kilowatts used. Then multiply that number by the amount your electric company charges per kilowatt hour. HID lights will use the number of watts it emits per hour, ie; 600w system will use 600 watts per hour (regardless of spectrum).
(light wattage output / 1000) x electricity cost per kilowatt hour =
Operating cost per hour operating cost per hour x hours used per month =
Operating cost per month
LED Grow Lights?
I personally haven't used LED lights extensively yet, I'm having great success without them. Many people swear by them however. A 90 watt LED light system has the same output power as a 400 watt HPS or MH bulb. They are advertised as the most efficient and coolest running grow lights available. LED grow lights are not recommended for use with ornamental plants as they give plants an unnatural sickly appearance when the light is on.Why Should I Use LED Grow Lights?
LED Grow Lights Compared To Fluorescent Lights
Use of Reflectors in Hydroponic and Indoor Grow light Systems.
The type and style of reflector used can make a tremendous difference in growing results ! Most reflectors come with a 85 -95% reflective, textured aluminum insert or a reflective spectral pebble insert.
You can also use natural sunlight to grow indoors and skip the expense of purchasing garden grow lights. This can be done with a greenhouse, solar room, or even a large window that gets plenty of sunlight. You can also do the reverse of this and grow outdoors hydroponically. Hydroponics only means that the growing system is soil-less, not necessarily that it is an indoor setup.